Re: missing ARP reply

On 11/11/24 21:36, Gary Aitken wrote:
> I'm having trouble with my solar inverter connecting to its home
> base somewhere in Germany and am suspecting a problem with a missing
> ARP reply.
...
> xxx.yyy is the inverter on the local network xxx.zzz is the fbsd
> gateway/router on the local network
> 
> #tcpdump -flnt -i fxp0 | grep 192.168.xxx.yyy ARP, Request who-has
> 192.168.xxx.zzz (aa:bb:cc:dd:ee:ff) tell 192.168.xxx.yyy, length 46 
> IP 192.168.xxx.yyy.3337 > 147.185.237.1.22222: Flags [.], seq
> 26043:26065, ack 708198036, win 2144, length 22 IP
> 147.185.237.1.22222 > 192.168.xxx.yyy.3337: Flags [P.], seq 1:23, ack
> 22, win 18410, length 22 IP 192.168.xxx.yyy.3337 >
> 147.185.237.1.22222: Flags [.], ack 23, win 2144, length 0
> 
> I'm guessing the 3 packets exchanged are a power optimizer reporting
> in, but may be the inverter doing something.
> 
> The arp table on xxx.zzz has a permanent entry for itself on the
> interface, picked up from /etc/hosts:
> 
> # arp -a ns.dreamchaser.org (192.168.xxx.zzz) at aa:bb:cc:dd:ee:ff on
> fxp0 permanent [ethernet]
> 
> Thoughts on why I am not seeing a reply to the ARP request?

My error; tcpdump does not print the destination host address in the ARP
reply, so grep didn't catch it.  duh.  Should have been

   tcpdump -flnt -i fxp0 | grep ARP
or
   tcpdump -flnt -i fxp0 | grep aa:bb:cc:dd:ee:ff

Gary